>> I was just trying that as I read your post. I'll drain some HW off
>> and see if that does anything.
>>
...if it's gravity hot water, it won't have an immediate effect on the boiler as the heating is an "indirect" circuit.
(Having a hot water cylinder doesn't necessarily mean it's gravity - it could be fully-pumped with a three-port valve. If it is, the valve being stuck is another suspect, since it carries out a switching function when it moves).
|